Radiation is one method to treat cancer and other diseases of the body. Brachytherapy is a general term for the radiation treatment of cancer at close distances inside the body. During brachytherapy, an applicator enclosing a radioactive source or sources is positioned within a body region targeted for treatment. The radioactive sources are typically wires with an end portion that emits radiation, or alternatively capsule type structures of radioactive materials. As used herein, the term radioactive source encompasses wires, capsules or other structures of radioactive materials In one type of brachytherapy, radioactive sources are temporarily placed in target treatment regions in the patient. To prevent human handling of the radioactive material and harmful exposure to radiation, a machine called an “afterloader” or “remote afterloader” may be used to load and unload the radioactive material into and from guide tubes that extend toward the applicator positioned within a patient.
Remote afterloaders allow for the accurate advancement and retraction of radioactive sources over a specified distance for a specified time period. A remote afterloader generally includes multiple channels, may hold more than one radioactive source, and uses controllers and drive mechanisms to advance and retract the radioactive source(s) through multiple ports attached to a rotating wheel that allows multiple guide tubes (previously placed into the patient) to be hooked up to the afterloader at the same time. The remote afterloader usually sends out a simulation member to check the patency of the guide tube without subjecting the patient to undue radiation exposure, and then sends out the radioactive source. After the treatment is performed through a first guide tube, the afterloader retracts the source into the shielding safe inside the afterloader, a wheel turns and aligns the next slot containing a guide tube to the shielded safe exit port. The remote afterloader then repeats its function sending and retracting the simulation member and radioactive member through this second tube. The procedure is repeated until the treatment prescription is carried out through all the specified transport tubes. FIG. 1 shows a prior art afterloader with multiple guide tubes attached.
One problem with current afterloader systems is that in order to verify that the correct applicator channel is correctly attached to the planned treatment port of the afterloader via a guide tube, the operator must visually inspect the attachment of the applicator to the guide tube, and the attachment of the guide tube to the afterloader port. If multiple guide tubes are used for treatment, each attachment must be checked by the operator. Because this involves a manual process, the possibility of human error exists, which may result in the wrong treatment being administered to the patient. Another problem is that even though the correct applicator is attached to a guide tube, the operator may not notice that the attachment is not secure, resulting in the unwanted exposure of the radioactive source to the patient or operator. Current devices include a mechanical gate (as illustrated in FIG. 2) to prevent the radioactive source from being ejected uncontrollably into the patient, but a patient may still receive an unwanted whole body dose of radiation if the gate blocks or traps the radioactive source during retraction.
In a related problem, in order to exchange an old or used radioactive source contained in the afterloader for a new radioactive source, an operator has to attach one end of a guide tube to an empty chamber in a source container chamber, and then connect the other end of the guide tube to the afterloader, as illustrated in FIG. 3. The old radioactive source then has to be downloaded into an empty chamber in the source container chamber. Following the download, the radioactive source is locked into the chamber and the transfer guide tube is detached from the now occupied chamber of the source container chamber, and then reattached to the chamber containing the new radioactive source. The new source is then uploaded into the afterloader. At this point the operator has to manually enter the radioactive source serial number and calibration data into the afterloader computer system. Again, because this is a manual process, the uploading and downloading of radioactive sources, as well as the input of radioactive source data, is prone to human error. Problems related to the secure attachment of the guide tube to the afterloader and source container chamber also exist, as described above with respect to the attachment of an applicator to the guide tube.